1. Field of the Invention
The present invention relates to surgical instruments for applying surgical fasteners or staples to body tissue, and more particularly to controlled closure mechanisms for controlling the spacing between the jaw members between which the tissue passes during the fastening or stapling procedure.
2. Discussion of the Prior Art
Surgical stapling or fastening devices having means for controlling the spacing between the jaw members are well known in the art. These devices typically include indicating means to provide a reading of the spacing between the jaw members.
Various controlled closure mechanisms are provided in the prior art for use with surgical stapling and fastening devices. The most notable of these devices utilize a complex worm gear type arrangement or screw bearing member to open and close the spacing between the jaw members of the surgical stapling or fastening apparatus. These devices generally provide a rotatable knob or wing-like assembly at the trigger end of the device remote from the jaw mechanism which carries the staple or fastener cartridge. A screw like mechanism is used to open and close the spacing between the jaws. As the jaw members are fit around a tissue site to which the staples or fasteners are to be applied, the surgeon must grasp the device with one hand while rotating the knob or wing-like assembly with the other hand. As the jaw members close about the tissue to pinch the tissue therebetween, the surgeon then activates the trigger mechanism to drive the staples or fasteners into the tissue. Several known devices provide an indicator means near the rotatable knob which gives a visual indication of the spacing between the jaw members.
The prior art devices are subject to several disadvantages in both use and construction which render these devices difficult to operate and expensive to manufacture. Many of the devices are cumbersome in use in that the surgeon must operate the device with both hands, holding the body of the instrument in one hand, while rotating the knob or wing assembly with the other hand. This may lead to inaccurate stapling or fastening since the surgeon is unable to guide the tissue to be stapled or fastened with his free hand while closing the jaws about the tissue. Furthermore, the number of interacting components provides inaccuracies due to normal buildup of tolerances. In addition, the gear arrangement may become worn during extended use, thus rendering an imprecise grasping action at the jaws.
Furthermore, the prior art devices generally involve a complex construction in which a precisely machined or cast worm gear must be constructed and incorporated into the device. This of course increases the cost of manufacture, and requires a complex assembly procedure to properly locate the worm gear in the instrument to control the spacing between the jaws.
Typical devices having a rotatable knob at the end portion adjacent the handle mechanism of a surgical stapling or fastening device are disclosed in, among others, U.S. Pat. No. 4,930,503 to Pruitt, U.S. Pat. No. 4,788,978 to Strekopytov et al., and U.S. Pat. No. 4,606,344 to Di Giovanni. In each of these devices, an elongated rod member having screw threads machined thereon is provided. The rod member connects a rotatable knob positioned adjacent the handle members to a pusher mechanism which urges a movable jaw in a forward direction toward a stationary jaw to close the spacing between the jaw members. When a desired spacing is reached, the trigger mechanism may be activated to fire the staples or fasteners through the tissue into the anvil member mounted on the stationary jaw. To remove the stapling or fastening instrument after application of the staples or fasteners, the knob is rotated in an opposite direction which turns the screw threaded rod to move the movable jaw member away from the stationary jaw member so that the entire device may be removed from the tissue.
Surgical stapling or fastening instruments having a wing-like arrangement positioned adjacent the handle assembly of the device for moving a movable jaw toward a stationary jaw for affixing surgical staples or fasteners to tissue are disclosed in U.S. Pat. No. 4,442,964 to Becht and U.S. Pat. No. 3,795,034 to Sterkopytov et al. These devices are similar to those described above except for the provision of a rotatable wing member in place of the rotatable knob. These devices also provide a screw threaded rod member which, when rotated, urges a movable jaw towards a stationary jaw to close the spacing between the jaw members around tissue to be stapled or fastened. After the application of surgical staples or fasteners, the wing assembly is rotated in an opposite direction to draw the movable jaw away from the stationary jaw so that the instrument may be removed from the tissue.
The novel surgical stapling or surgical fastening device of the present invention obviates the disadvantages encountered in the prior art and provides an efficient controlled closure mechanism for controlling the spacing between the jaw members of the surgical stapling or fastening apparatus. The device of the present invention allows a surgeon to operate a surgical stapler or fastener with one hand while freeing the other hand to assist in the surgical procedure. Furthermore, the present invention is of lightweight construction and provides ease of handling by a thumb controlled closure mechanism which permits the surgeon to set the spacing between the jaw members and fire the device while using only one hand.